294881-12-2Relevant academic research and scientific papers
Tuning charge recombination rate constants through inner-sphere coordination in a copper(I) donor-acceptor compound
Scaltrito, Donald V.,Kelly, Craig A.,Ruthkosky, Mark,Zaros, Mark C.,Meyer, Gerald J.
, p. 3765 - 3770 (2000)
The coordination compounds [Cu(bpy-MV2+)(PPh3)2](PF6)3, where bpy-MV2+ is the 1-(4-(4'-methyl-2,2'-bipyridin-4-yl)butyl)-1'-methyl-4,4'-bipyridinediium(2+) cation, and [Cu(dmb)(PPh3)2](PF6), where dmb is 4,4'-dimethyl-2,2'-bipyridine, have been prepared and characterized. Visible light (417 nm) excitation of [Cu(bpy-MV2+)(PPh3)2]3+ at room temperature leads to rapid intramolecular electron transfer, k(cs) > 1 x 108 s-1, to form a charge-separated state with an electron localized on the pendant viologen group and a copper(II) metal center, abbreviated [Cu(II)-bpy-MV·+]. This state recombines to ground-state products with first-order rate constants that can be tuned with solvent over a ~107 - 105 s-1 range. The activation parameters were determined from temperature-dependent electron-transfer data with Arrhenius analysis. A model is proposed wherein a solvent molecule is coordinated to Cu(II) in the charge-separated state, [(S)Cu(II)-bpy-MV·+]. Visible light excitation of [Cu(dmb)(PPh3)2](PF6) in argon-saturated dichloromethane produces long-lived photoluminescent excited states, τ = 80 ns, that are dynamically quenched by the addition of Lewis basic solvents. The measured quenching constants each correlate well with the lifetime of the charge-separated state measured after excitation of [Cu(bpy-MV2+)(PPh3)2]3+ in the corresponding solvent.
